These is what I found under event viewer (pc):
General:
Type: Microsoft.Dynamics.Nav.Client.NavClientClosingException
Fatal: True
ShowError: True
Message: The connection to the server has been lost. The application will close.
StackTrace:
at Microsoft.Dynamics.Nav.Client.ConnectionStateManager.HandleCommunicationFailure[T](CallServerMethod`1 callServerMethod, ServerCallOptions options, Exception e, Int32 messageNumber, String sessionId)
at Microsoft.Dynamics.Nav.Client.ConnectionStateManager.CallServer[T](CallServerMethod`1 callServerMethod, ServerCallOptions options)
at Microsoft.Dynamics.Nav.Client.ConnectionStateManager.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServerInvocationHandler.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServiceConnection.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServiceConnectionBase.OpenForm(NavOpenFormArguments& mainForm, NavOpenFormArguments[]& subForms)
at Microsoft.Dynamics.Nav.Client.ServiceConnection.Microsoft.Dynamics.Nav.Client.IService.OpenForm(NavOpenFormArguments& , NavOpenFormArguments[]& )
at Microsoft.Dynamics.Nav.Client.DataBinder.NstDataAccess.OpenForm(LogicalForm mainForm, Collection`1 subForms)
at Microsoft.Dynamics.Nav.Client.UIPatterns.OnFormOpeningPattern.OpenForm(LogicalForm form)
at Microsoft.Dynamics.Nav.Client.UIPatterns.OnFormOpeningPattern.FormBuilt(Object sender, EventArgs e)
at Microsoft.Dynamics.Framework.UI.LogicalForm.OnFormBuilt(EventArgs e)
at Microsoft.Dynamics.Framework.UI.LogicalForm.BuildForm()
at Microsoft.Dynamics.Nav.Client.Builder.NavSessionHelper.BuildForm(LogicalForm form)
at Microsoft.Dynamics.Nav.Client.FormBuilder.PageBuilder.Build(MasterPage definition, BindingManager bindingManager, UIBuilderContext context)
at Microsoft.Dynamics.Nav.Client.FormBuilder.PageBuilder.Build(MasterPage definition, UIBuilderContext context)
at Microsoft.Dynamics.Nav.Client.FormBuilder.UIBuildManager.BuildPage(MasterPage pageDef, UIBuilderContext context)
at Microsoft.Dynamics.Nav.Client.FormBuilder.BuilderSession.CreateLogicalForm(MasterPage metadata, FormState formState)
at Microsoft.Dynamics.Nav.Client.PageRunCallbackHandler.RunModalPage(FormRunModalRequest formRequest, LogicalForm parentForm)
at Microsoft.Dynamics.Nav.Client.ServiceClientCallback.<>c__DisplayClass1d.<FormRunModal>b__1c()
at Microsoft.Dynamics.Nav.Client.ServiceClientCallback.<>c__DisplayClass1.<RunClientRequest>b__0()
at Microsoft.Dynamics.Nav.Client.ServerInvocationManager.<>c__DisplayClass2.<WaitForServerResponse>b__0()
at Microsoft.Dynamics.Nav.Client.ServerInvocationManager.DoClientRequestAndCatch(Action clientRequest, Action`1 sendToServerIfNotFaulted)
at Microsoft.Dynamics.Nav.Client.ServerInvocationManager.WaitForServerResponse(IAsyncResult asyncResult, ThreadCallbackContext threadEventContext)
at Microsoft.Dynamics.Nav.Client.ServerInvocationManager.CallServer[T](CallServerMethod`1 callServerMethod, ServerCallOptions options)
at Microsoft.Dynamics.Nav.Client.ServerInvocationHandler.CallServer[T](CallServerMethod`1 callServerMethod, ServerCallOptions options)
at Microsoft.Dynamics.Nav.Client.ConnectionStateManager.CallServer[T](CallServerMethod`1 callServerMethod, ServerCallOptions options)
at Microsoft.Dynamics.Nav.Client.ConnectionStateManager.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServerInvocationHandler.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServiceConnection.CallServer[T](CallServerMethod`1 callServerMethod)
at Microsoft.Dynamics.Nav.Client.ServiceConnectionBase.ActionField(NavRecordState& state, NavDataSet recDataSet, Int32 controlId)
at Microsoft.Dynamics.Nav.Client.ServiceConnection.Microsoft.Dynamics.Nav.Client.IService.ActionField(NavRecordState& , NavDataSet , Int32 )
at Microsoft.Dynamics.Nav.Client.DataBinder.NstDataAccess.ActionMethod(Int32 controlId)
at Microsoft.Dynamics.Nav.Client.Actions.InvokePageTriggerAction.InvokeTrigger(LogicalControl logicalControl, UISession uiSession)
at Microsoft.Dynamics.Nav.Client.Actions.InvokePageTriggerAction.InvokeCore(Boolean async, LogicalControl logicalControl, Object state, UISession uiSession)
at Microsoft.Dynamics.Framework.UI.LogicalAction.InvokeCoreWithErrorHandling(Boolean async, LogicalControl logicalControl, Object state, UISession uiSession)
at Microsoft.Dynamics.Framework.UI.LogicalAction.DoInvoke(LogicalControl logicalControl, UISession uiSession)
at Microsoft.Dynamics.Framework.UI.ActionControl.Invoke()
at Microsoft.Dynamics.Framework.UI.Windows.ActionsHelper.<>c__DisplayClassa.<ModalitySafeInvoke>b__8()
at Microsoft.Dynamics.Framework.UI.Windows.ActionsHelper.ModalitySafe(Action action)
at Microsoft.Dynamics.Framework.UI.Windows.ActionsHelper.ModalitySafeInvoke(ActionControl actionControl)
at Microsoft.Dynamics.Framework.UI.Windows.ActionControlAdapterBase.DefaultInvokeAction(LogicalControlAdapter adapter, ActionControl actionControl)
at Microsoft.Dynamics.Framework.UI.Windows.ActionControlAdapterBase.DefaultInvokeAction(LogicalControlAdapter adapter)
at Microsoft.Dynamics.Framework.UI.UX2006.WinForms.LogicalCommand.Execute(Object parameter)
at MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated)
at System.Windows.Controls.Primitives.ButtonBase.OnClick()
at System.Windows.Controls.Button.OnClick()
at Microsoft.Windows.Controls.Ribbon.RibbonButton.OnClick()
at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(ApplicationContext context)
at Microsoft.Dynamics.Nav.Client.WinClient.NavWinFormsClientSession.RunMessagePump()
at Microsoft.Dynamics.Nav.Client.WinClient.NavWinFormsClientSession.RunCore()
at Microsoft.Dynamics.Framework.UI.Windows.ClientSessionBase.Run()
at Microsoft.Dynamics.Nav.Client.WinClient.NavClientErrorHandler.ExecuteAndCatchExceptions(Func`1 execute)
Source: Microsoft.Dynamics.Nav.Client.ServiceConnection
HResult: -2146233088